If I had to choose a number 1, one place I want to go to / see more than all others, I think it would be Area 51. I've been kinda intrigued / obsessed ever since the first article or documentary I saw years (decades?) ago. (No, I don't believe there are aliens there.)
But other than that:
Not quite narrowed down to only ten. In (more or less) alphabetical order:
Africa (Serengeti/Wildebeest migration, Kruger)
Alaska (Drive the Dalton Highway, watch the Grizzlies feeding)
Amazon rain Forest / Iguazu falls (I think these are totally separate, but somebody upthread combined them, so I will too)
Antarctica
Australian Outback
Banff/Jasper (I can't even count how many trips I had planned here but every time it ended up not happening for some reason.)
Canadian Ice Roads (Does this even count as a place?)
Climb Mt. Whitney (Not quite as sexy as K2 or Everest, but this I actually intend to do sometime within the next few years.)
New Zealand
Sahara Desert
the Alps
I would include Hawaii, but I already have a trip planned
Iceland / Northern Lights - done! (though I'm not quite sure why "Northern Lights" is a destination...)
Cross-USA road trip -done x9!!
Also
What I really want to go see is the Trinity test site in the white sands missile range. Unfortunately they only have public tours two days a year and always on Shabbos